Sound reproducing device



Aug. 22, 1933. J. G. JuHAsz 1,923,831

SOUND REPRODUCING DEVICE Filed May 27, 1931 Jaz/672 307 27a472z66 GZZI/zczz,

Patented Aug. 22, 1933 SOUND REPRODUCING DEVICE James G. Juhasz, Chicago, Ill.

Application TIay 27, 1931. Serial No. 540,445

1 Claim.

This invention relates to sound reproducing devices, and is particularly adapted to be embodied in loudspeakers, and the like, for public addresses and radio receivers.

One form of the invention is embodied in a loudspeaker which comprises an electro-magnet having a central pole and a pair of opposed outer poles, the construction being such that two relatively narrow arcuate magnetic gaps are provided. A cup-shaped member formed of magnetic material has a cylindrical portion which projects into the magnetic gaps and is mounted in such manner that it may reciprocate along its longitudinal axis. A conical diaphragm has its smaller end secured to the cup-shaped member, and it is provided with a flange at its base, which ange is secured in an annular frame-work.

Mounted upon the central pole piece is a voice coil which may be operatively connected to the output circuit of a radio receiver, or the like.

In the drawing:

Figure 1 is a central longitudinal section taken through a loudspeaker which embodies the invention` and Fig, 2 is a section taken on line 2-2 of Fig. 1.

Referring to the drawing wherein a preferred embodiment oi the invention is illustrated, the reference character l0 designates generally an electromagnet which comprises a central pole piece 11 and a U-shaped pole piece 12 provided with inwardly turned ends 13. rihe central pole piece 11 projects into the space between the ends 13 in such manner that two arcuate magnetic gaps 15 are formed. The winding for the electro-magnet is shown at 16, the winding 16 being carried by the central pole piece 11. Also mounted upon the central pole piece ll is a voice coil 18 which may be connected to the output circuit, or a radio receiver, or the equivalent.

A cup-shaped member 19 formed of magnetic material is provided with a cylindrical ange 20 which projects into the arcuate gaps 15. The sheet 21 may be made of impregnated fabric or sheet metal. The construction is well known in the art and it is readily understood that the sheet 21 is adapted to restore the cup-shaped member 19 to its neutral or unbiased position after it has been displaced as hereinafter explained.

The cup-shaped member 19 is secured to the smaller end of a conical diaphragm 22 which is provided at its outer end with an outwardly extending annular iiange 23. The periphery of the annular ange 23 is secured in an annular framework 24 carried by a irustro-conical member or basket 25 which has its smaller end secured to sheet 21.

The voice coil or winding 18 is connected to a source of audio frequencies, such as the output circuit of a radio receiver. The varying current in the winding 18 will increase and decrease the strength of the magnetic fields as the current in the voice coil increases or de- Greases.

Ii it is assumed that the voice coil is mounted in such manner that when the current flowing through it increases, the magnetic elds will be strengthened. It will be readily understood that when the current decreases the magnetic elds will be weakened. Such variance in the iiux density in the fields will cause the cupshaped member 19 to vibrate and it, in turn, will vibrate the diaphragm 22 and reproduce the sounds which produce the signals received by the radio receiver.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications.

Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claim, in which it is my intention to claim all novelty inherent in my invention as broadly as possible, in view'of the prior art.

What I claim as new, and desire to secure by Letters Patent, is:

A sound reproducing device comprising an electro-magnet havinga central pole-piece and an outer pole-piece, said pole-pieces co-operating to form an annular magnetic iield, a winding on said central pole-piece adapted to be connected to a Source of direct current to energize the electro-magnet, a second winding on said central pole-piece adapted to be connected to a source oi current modulated by audio-frequencies, a cup-shaped member formed from magnetic material and provided with a cylindrical wall disposed in said magnetic eld, a flexible member supporting said cup-shaped member for movement in said field, and a conical diaphragm having its smaller end xed with respect to said cup-shaped member.

JAMES G. JUHASZ. 

